In the practice of diagnostic medicine, it is often necessary or desirable to perform a biopsy, or to sample selected tissue from a living patient for medical evaluation. Cytological and histological studies of the biopsy sample can then be performed as an aid to the diagnosis and treatment of disease. Biopsies can be useful in diagnosing and treating various forms of cancer, as well as other diseases in which a localized area of affected tissue can be identified.
Biopsies are routinely performed on tissue using a needle set, which typically includes an outer cannula defining a lumen and having a pointed tissue piercing tip and a proximal tissue receiving aperture. The needle set also includes an inner cannula slidably disposed within the outer cannula so that the aperture can be alternately opened and closed. The inner cannula has an open distal end with a cutting blade to excise tissue prolapsing through the aperture and into the lumen of the outer cannula. Typically, a hub is connected to the proximal end of each of the outer and inner cannulas. Such needle sets are used with or incorporated in various forms of biopsy devices, including motor driven biopsy devices.
Also, current motor driven biopsy devices can be larger than ideal due to the size of the components required to perform various steps of the biopsy. An overly large motor driven biopsy device can cause a biopsy procedure to be less than ideal. For instance, while ultrasound guided biopsy can be the most straightforward approach for guiding the biopsy device, lesions better seen on mammography images, particularly microcalcifications, require stereotactic localization. Stereotactic localization involves obtaining a pair of x-ray images. Thus, biopsy devices designed for stereotactic use must be sufficiently narrow to avoid interfering with the stereotactic localization pairs of x-ray images.